As effects of catechins, there have been reported a suppressing effect on the increase of cholesterol and an inhibitory effect on α-amylase activity (see, for example, JP-A-60-156614 and JP-A-03-133928). For such physiological effects to manifest, it is necessary for an adult to drink tea as much as 4 to 5 cups a day. Accordingly, there has been a great demand for a technological method by which catechins can be added to beverages at a high concentration in order to facilitate the ingestion of a large amount of catechins. As one of the methods for this, catechins are added in a dissolved form to a beverage by using a green tea concentrate (see, for example, JP-A-59-219384, JP-A-4-20589 and JP-A-61-130285) or the like.
Where non-polymer catechins are extracted from tea leaves at high concentration for adding them at high concentration in a beverage, there is an inevitable drawback that compared with general beverages containing non-polymer catechins at low concentration, not only the bitterness and astringency derived from the non-polymer catechins but also the bitterness of caffeine, acridness of unidentified ingredients and the like synergistically increase, resulting in a beverage having the flavor and taste which are considerably different from those inherent to tea.